The disclosure of Japanese Patent Application No. 11-353528 filed on Dec. 13, 1999 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to controlling deployment of an air-bag body of a head-protection air-bag device. More particularly, the invention relates to controlling deployment of an air-bag body of a head-protection air-bag device including a side-impact sensor and a rollover sensor in which the air-bag body is deployed and inflated like a curtain along the side of the vehicle compartment.
2. Description of Related Art
In order to improve the capability of protecting the head of an occupant seated in the front seat against a predetermined high load applied to the side of the vehicle body, there has been proposed a head-protection air-bag device having an air-bag body stored in a folded state along the roof side rail. In this head-protection air-bag device, the air-bag body inflates like a curtain along the side window glass. Hereinafter, the structure of the aforementioned head-protection air-bag device disclosed in U.S. Pat. No. 5,788,270 will be described.
As shown in FIG. 10, this head-protection air-bag device 100 is mainly composed of an elongate duct 106 extending from a front pillar portion 102 along a roof side rail portion 104, an air-bag body 112 stored in the folded state within the duct 106 and fixed to the vehicle body at a front-end fixing point 108 and a rear-end fixing point 110, an inflator 116 connected to the rear end of the duct 106 through a hose 114, for injecting a gas in response to a predetermined high load applied to the side of the vehicle body, and a band-shaped strap 118 having its one end fixed to the vehicle body and the other end fixed to the rear end of the air-bag body 112. The air-bag body 112 is formed by a plurality of substantially cylindrical cells 120 connected to each other with their longitudinal axes being oriented approximately in the vertical direction of the vehicle.
The aforementioned structure causes the gas to be injected from the inflator 116 when the predetermined high load is applied to the side of the vehicle body. The injected gas flows in each cell 120 of the folded air-bag body 112 through the hose 114 and the duct 106. As a result, each cell 120 inflates into a substantially cylindrical shape along the longitudinal axis of the vehicle. Thus, the air-bag body 112 inflates like a curtain along a window glass 122. Moreover, the rear end of the air-bag body 112 is connected to the vehicle body through the strap 118 so as to be reliably located inside the top portion of a B-pillar (i.e., a center pillar) portion 124.
However, in such a head-protection air-bag device, the air-bag body 112 must be instantaneously deployed and inflated upon lateral collision (side collision) of the vehicle. Therefore, in the early stage of the deployment, the air-bag body 112 is subjected to a high gas-pressure as well as the inflation force of the air-bag body itself. Accordingly, the air-bag body 112 may be damaged to cause gas leakage, and an internal-pressure retention time may be reduced. As a result, in case of rollover of the vehicle that requires a long internal-pressure retention time, the thickness of a sealant applied to the surface of the air-bag body and the weaving density of the bag must be increased in order to prevent the damage to the air-bag body. However, this results in a bulky air-bag body in the folded state, thus requiring a larger storage space.
Therefore, a need exists for controlling deployment of an air-bag body of a head-protection airbag device, in which the internal-pressure retention time can be increased in the case of rollover without increasing the bulk of the airbag body in the folded state.
The present invention controls deployment of an air-bag body of a head-protection air-bag device, in which the internal-pressure retention time can be increased in the case of the rollover without increasing the bulk of the air-bag body in the folded state.
In a method for controlling deployment of an air-bag body of a head-protection air-bag device provided with a side-impact sensor and a rollover sensor according to a first aspect of the invention, the air-bag body is deployed and inflated like a curtain along a side of a vehicle compartment by a gas injected from an inflator that is actuated in response to a detection signal output from the respective sensors. The method includes the steps of injecting high pressure gas from the inflator when the side-impact sensor detects side collision, and injecting low pressure gas from the inflator when the rollover sensor detects rollover.
Accordingly, when the side-impact sensor detects side collision, the inflator is actuated such that the high pressure injected gas flows into the air-bag body. As a result, the air-bag body is instantaneously deployed and inflated to protect the head of the occupant. When the rollover sensor detects rollover of the vehicle, the inflator is actuated such that the low pressure injected gas flows into the air-bag body. As a result, in the case of the rollover, the damage to the air-bag body due to the gas pressure can be reduced, and therefore, gas leakage resulting from the damage can be reduced. This may increase the internal-pressure retention time, whereby movement of the air-bag body toward the outside of the vehicle while constraining the occupant (in the deployed state) can be regulated for a longer time. Moreover, it is no longer necessary to increase the thickness of the sealant applied to the surface of the air-bag body and the weaving density of the bag in case of the rollover. Therefore, the bulk of the air-bag body in the folded state is not increased, and a large storage space, thus, is not necessary. Moreover, in the case of the rollover, the air-bag body is deployed at a low expansion pressure. Therefore, the damage to the interior parts such as garnish and assist grip can be reduced, allowing reduction in the repair cost.
In a method for controlling deployment of an air-bag body of a head-protection air-bag device provided with a side-impact sensor and a rollover sensor according to the second aspect of the invention, the air-bag body is deployed and inflated like a curtain along a side of a vehicle compartment by a gas injected from an inflator that is actuated in response to a detection signal output from the respective sensors. The method includes the steps of reducing a time for an internal pressure of the air-bag body to reach a peak value by the injected gas from the inflator when the side-impact sensor detects side collision; and increasing a time for an internal pressure of the air-bag body to reach a peak value by the injected gas from the inflator when the rollover sensor detects rollover.
Accordingly, when the side-impact sensor detects side collision, the inflator is actuated, and the internal pressure of the air-bag body quickly reaches the peak value. As a result, the air-bag body is instantaneously deployed and inflated, protecting the head of the occupant. When the rollover sensor detects rollover of the vehicle, the inflator is actuated, and the internal pressure of the air-bag body reaches the peak value, taking a longer time than that taken by the side collision case. As a result, in the case of the rollover, the damage to the air-bag body due to the rapid increase in the internal pressure can be reduced, and therefore, gas leakage resulting from the damage can be reduced. Accordingly, the internal-pressure retention time is increased, whereby the movement of the air-bag body toward the outside of the vehicle while constraining the occupant (in the deployed state) can be regulated for a longer time. Moreover, it is no longer necessary to increase the thickness of the sealant applied to the surface of the air-bag body and the weaving density of the bag, in case of the rollover. Therefore, bulk of the air-bag body in the folded state is not increased, and a large storage space, thus, is not necessary. Moreover, in the case of the rollover, the expansion pressure upon deployment of the air-bag body rises at a relatively lower speed. Therefore, the damage to the interior parts such as garnish and assist grip can be reduced, allowing reduction in the repair cost.
Note that each of the above-mentioned aspects is also applicable to a vehicle provided with an air-bag body having such a shape that protects the heads of the occupants in the front and rear seats, and a vehicle provided with an airbag body having such a shape that protects the heads of the occupants in the front seat, second-row seat, and third-row seat of the vehicle.
These and other aspects of the present invention will become readily apparent upon further review of the following specification and drawings.